#include<stdio.h>
#define CARD_SIZE 10000

int card[CARD_SIZE], temp_a[CARD_SIZE], temp_b[CARD_SIZE], temp_c[CARD_SIZE];

void shuffle(int x, int y, int n);

int main(void)
{
	int n, m, p, q, r,
		i, count = 0,
		s[2][CARD_SIZE];
	
	scanf("%d%d%d%d%d", &n, &m, &p, &q, &r);
	for(i = 0; i < m; i++)
		scanf("%d%d", &s[0][i], &s[1][i]);

	for(i = 0; i < n; i++)
		card[i] = i + 1;

	for(i = 0; i < m; i++)
		shuffle(s[0][i], s[1][i], n);

	for(i = p - 1; i < q; i++)
		if(card[i] <= r) count++;
	
	printf("%d\n", count);
	
	return 0;
}

void shuffle(int x, int y, int n)
{
	int i, j;
//divide deck
	for(i = 0; i < x; i++)
		temp_a[i] = card[i];
	for(j = 0; i < y; i++, j++)
		temp_b[j] = card[i];
	for(j = 0; i < n; i++, j++)
		temp_c[j] = card[i];
//rebuild deck
	for(i = 0; i < (n-y); i++)
		card[i] = temp_c[i];
	for(j = 0; i < (n-x); i++, j++)
		card[i] = temp_b[j];
	for(j = 0; i < n; i++, j++)
		card[i] = temp_a[j];
}